This invention generally relates to the field of occluding devices, delivery systems for such devices and the method of using such devices and systems in the occlusion of body passageways. The invention is particularly useful for the occluding reproductive lumens such as a female patient's fallopian tubes or a male patient's vas deferens to affect contraception.
Conventional contraceptive strategies generally fall within three categories: physical barriers, drugs and surgery. While each have certain advantages, they also suffer from various drawbacks. Barriers such as condoms and diaphragms are subject to failure due to breakage, displacement and misplacement. Drug strategies, such as the pill and Norplant™, which rely on artificially controlling hormone levels, suffer from known and unknown side-effects from prolonged use. Surgical procedures, such as tubal ligation and vasectomy, are very effective, but involve the costs and attendant risks of surgery, and are frequently not reversible.
Recently, minimally invasive treatments have be proposed which deploy occluding stent-like devices within reproductive lumens, e.g. the fallopian tubes or vas deferens, as a contraceptive alternative to tubal ligation or vasectomy. However, placing a stent or similar occluding device may not create sufficient or permanent obstruction of the reproductive lumen depending on the nature of the obstructive device. For example, the obstructive device may be too small to provide complete obstruction of the reproductive lumen, or the device may be permeable to cell movement. An occluding device placed in a reproductive lumen, for example, may not securely seal against the luminal walls, or may initially allow egg cells or sperm cells to pass through the device until tissue growth completes the occlusion of the reproductive lumen and thus allow pregnancy to occur. Additionally, the occluding device might create an initial obstruction sufficient to prevent the passage of an egg but allow sperm cells to pass through or by the occluding device, fertilizing an egg upstream of the obstruction and resulting in an ectopic pregnancy.
The use of an occluding contraceptive or sterilization device, particularly with mesh or fibrous material to promote tissue ingrowth, has been proposed (See for example U.S. Pat. Nos. 6,096,052 and 6,432,116). However, with these devices there is an initial period (several weeks to several months) after deployment during which the patient is at risk for cell passage through the device that can result in pregnancy. In such situations it may be desirable to use a supplemental method of birth control until tissue ingrowth effectively occludes the fallopian tube. The same initial risks are found when occluding a male's vas deferens.
Even in situations in which complete obstruction has been achieved initially, the body lumen may recannalize. For example, an obstruction placed in a fallopian tube may create an initial blockage that obstructs passage of sperm or eggs. However, over time the walls of the tube may reconfigure to create a channel around the obstruction, effectively recannalizing the fallopian tube.